From 7d19666cff378bf0d5d5c25dfff1b25069d39953 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Gustav=20S=C3=B6rn=C3=A4s?= <gustav@sornas.net>
Date: Wed, 26 Jan 2022 23:38:23 +0100
Subject: jump address in adr-field

---
 lab1asm.py   | 11 ++++-------
 test_bra.out | 20 ++++++++++----------
 2 files changed, 14 insertions(+), 17 deletions(-)

diff --git a/lab1asm.py b/lab1asm.py
index dfe9fb3..f6c7997 100644
--- a/lab1asm.py
+++ b/lab1asm.py
@@ -42,14 +42,10 @@ def compile(lines):
                 ))
             case [inst, label]:
                 assert inst in ("bra", "bne", "bge", "beq")
-                compiled.append("{:02x}: {:01x}000".format(
+                compiled.append("{:02x}: {:01x}0<{}>".format(
                     addr,
                     OPS[inst],
-                ))
-                addr += 1
-                compiled.append("{:02x}: <{}>".format(
-                    addr,
-                    label
+                    label,
                 ))
             case ["halt"]:
                 compiled.append("{:02x}: {:01x}000".format(addr, OPS["halt"]))
@@ -63,7 +59,8 @@ def compile(lines):
     linked = []
     for line_nr, line in enumerate(compiled):
         for label, label_nr in labels.items():
-            line = line.replace(f"<{label}>", f"{label_nr - line_nr:04x}")
+            rel_pos = (label_nr - line_nr + 0xff) & 0xff
+            line = line.replace(f"<{label}>", f"{rel_pos:02x}")
         linked.append(line)
 
     return linked, labels
diff --git a/test_bra.out b/test_bra.out
index 22b9374..58ef61b 100644
--- a/test_bra.out
+++ b/test_bra.out
@@ -1,14 +1,14 @@
 PM:
-00: 6000
-01: 0005
-02: 0100
-03: 00ee
-04: 101a
-05: 8000
-06: 0100
-07: 00ff
-08: 101a
-09: 8000
+00: 6004
+01: 0100
+02: 00ee
+03: 101a
+04: 8000
+05: 0100
+06: 00ff
+07: 101a
+08: 8000
+09: 0000
 0a: 0000
 0b: 0000
 0c: 0000
-- 
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